For over 25 years now, medical bacteriologists all over the world have turned to ‘Cowan and Steel’ as their first reference book when they encountered an unfamiliar bacterial isolate. A generation of laboratory workers has grown up with it. They turned to it not only because there was clear information on how to examine isolates, with concise details of culture media and test methods that were applicable to the great majority of bacteria of medical importance, but also because of the famous successive tables that led from genera with their minidefinitions to species with their characters. These were combined with practical hints on where one might go wrong, and succinct information on the pathogenic species. The tables contained carefully chosen data in just the right amount for a useful laboratory manual on the identification of medically important bacteria.

In the years since the last edition, test methods and the variety of bacteria of medical interest have both grown considerably. Not only have poorly studied areas like the ‘diphtheroids’ been much clarified, but a number of newly recognized pathogens such as legionellae have become important. Medical and other workers will therefore welcome this new edition, which follows closely the emphasis and style of its predecessors. The contributors and editors are to be congratulated on their labours in bringing a complex field to the concise summary that is contained here, often in the face of difficulties in finding convenient diagnostic tests for the newer taxa.